1. Field of the Invention
The present invention relates to a tape winder and, more in particular, to a winder for winding a long and narrow piece of matter such as a magnetic tape and the like on a winding shaft in a roll shape.
2. Description of the Related Art
Japanese Patent Application Publication No. 6-329308 discloses a tape winder, which comprises a pressure roll rotationally contacting the outer peripheral surface of a tape roll at a winding time, a wind pressure device which blows an air to the outer peripheral surface of the tape roll at the winding time, and a movable portion moving device which displaces the pressure roll and the wind pressure device according to a winding diameter of the tape roll. In this winder, when the wind pressure applied to the tape roll fluctuates, there occur various troubles. For example, when the wind pressure decreases, the air caught between the tape winds increases and there occur troubles in that the tape winding becomes loose and the edges of the wound tape are not aligned. On the contrary, when the wind pressure increases, the winding tightness increases, and an adverse effect is inflicted upon the quality to cause the increase of the winding tightness, a damage on the tape and the like. Thus, it is necessary always to keep a constant control of the distance between a nozzle which is a wind pressure device and the outer peripheral surface of the tape roll so that the wind pressure applied to the outer peripheral surface of the tape roll is kept constant.
As a control method of controlling a distance constant between the nozzle and the outer peripheral surface of the tape roll, there is a method in which a numerical calculation of a winding diameter is made from a tape traveling speed and a number of reel rotations and, according to this calculated winding diameter, a nozzle position is allowed to be moved backward. There is also a method in which the distance between the outer peripheral surface of the tape roll and the nozzle is measured by a laser displacement gage and the like and, according to this measured value, the nozzle position is controlled.
However, the method of making a numerical operation of a winding diameter requires an operation of the winding diameter including an eccentricity quantity of the tape roll at a high speed and, therefore, there is a problem in that not only an expensive high speed operational equipment, but also a complex control system for correcting a nozzle position at a high speed according to calculation results is required. Further, in the case where a fluctuation of a tape thickness is high, the nozzle sometimes contacts the outer peripheral surface of the tape roll, thereby inflicting a damage on it.
On the other hand, the method of measuring a distance requires correcting the nozzle position at a high speed according to a measurement result of the distance between the nozzle and the outer peripheral surface of the tape roll and, therefore, there is a problem in that it becomes difficult for the nozzle to follow the outer peripheral surface of the tape roll according as the number of rotations of a winding reel increases.
Moreover, the conventional tape winder has a drawback in that a mere constant control of the distance between the nozzle and the outer peripheral surface of the tape roll not only causes the edges of the wound tape to be not aligned when the tape is displaced in a width direction at a tape winding approach position immediately before the tape is wound, but also the wind pressure from the nozzle is biased in the width direction, so that the winding tightness becomes not uniform in the width direction of the tape.